1. Field of the Present Invention
The present invention generally relates to dissipating heat generated by an integrated circuit, and more specifically to an assembly for retaining a heatsink in contact with an integrated circuit and introducing an air duct around the heatsink.
2. History of Related Art
Market demands for processing intensive applications such as multimedia have resulted in an ever increasing demand for computing systems that operate at higher speeds. In addition, market preferences generally dictate that smaller packages are preferred to larger packages. Unfortunately for manufacturers and suppliers of such computing systems, thermal considerations generally dictate a preference for slower operating speeds and larger packages. To achieve market place success therefore, manufacturers must design increasingly efficient mechanisms and systems for dissipating heat within an electronic component such as a computer without significantly increasing cost, complexity, or package size
In the recent past, typically only the central processor of a computing system generated enough heat to warrant extensive heat dissipation consideration. More recently however, the higher operating speeds demanded of components peripheral to the central processor have resulted in the need to expand the number of components requiring heat dissipation mechanisms. For example, many computing systems include one or more peripheral interfaces that comply with various industry standard bus architectures such as the Industry Standard Architecture (ISA), Extended Industry Standard Architecture (EISA), or Peripheral Component Interface (PCI). These standards may require bus frequencies in excess of 100 MHz thereby creating significant thermal energy. In addition, the application hardware that is being developed for these architectures is becoming increasingly complex. Because the physical dimensions of expansion cards designed for such industry standard interfaces is constrained, however, designers of such cards must attempt to utilize every available square inch of the board if they are to fully implement today's advanced designs on a single expansion card.
Typically, heatsinks are used to assist in the thermal control of high speed, high power integrated circuits. At a time when heatsinks were most commonly mounted only to a central processing units that were located on a relatively large mother board, designers could afford to be less concerned about the amount of space required for the hardware necessary to secure the heatsink to the integrated circuit. If, for example, a heatsink required four screws, the holes necessary to receive these securing screws, and the amount of board space consumed by these holes did not pose a tremendous problem for the designer. As the number of heatsinks on an individual board has increased and the amount of board space available has decreased, the conventional methods of securing heatsinks to their associated devices has become increasingly problematic. In addition, it is not uncommon to further secure the contact between the heatsink and the integrated circuit with some form of thermally conductive paste or adhesive. As the complexity and cost of fabricating integrated circuits has increased and the market lifetime of products has decreased because of the accelerating rate at which advances are achieved, it has become increasingly important to be able to easily perform replacement and rework functions on circuit cards. Unfortunately, the prior methods of securing heatsinks to their associated integrated circuits using extensive hardware and adhesive made rework a difficult task. Therefore it would be desirable to implement a heat dissipation system that facilitated this important function.
In addition to the problems noted above, a common method of increasing the thermal dissipation capability of a system in the past has been to increase the size of the heatsinks themselves. As stated above, however, the demands for smaller packages and less costly devices run generally contrary to a philosophy of increasing the size of the heatsink with each succeeding generation of integrated circuits or surrounding the heatsinks with expensive hardware designed to either cool the ambient temperature or implement an alternative cooling medium such as liquid cooling systems. Therefore it is desirable to implement a heat dissipation system that provided a means for increasing the cooling capacity of a given heatsink without significantly increasing the cost or complexity of the resulting system.